9321341 Vohs The objectives of this project are to provide a comprehensive description of the surface-chemical phenomena involved in the growth of epitaxial layers of zinc selenide (ZnSe) on the (100) surface of gallium arsenide (GaAs) and to develop relationships between surface chemistry, film structure, and interfacial properties. The influence of surface reconstruction of a GaAs(100) substrate on the growth of epitaxial ZnSe films using metalorganic molecular-beam epitaxy (MOMBE) is studied. The adsorption and reaction of dimethylzinc, diethylzinc, and diethylselenium on the arsenic-rich c(4x4) and c(2x8) reconstructions and the nearly stoichiometric (1x6) reconstruction of GaAs(100) are investigated using temperature-programmed desorption and high-resolution electron-energy-loss spectroscopy (HREELS). These results are compared with those from previous studies on the gallium-rich (4x1) reconstruction. The morphology and surface structure of ZnSe films are characterized using atomic force microscopy and scanning tunnelling microscopy as functions of GaAs(100) substrate reconstruction and processing conditions (temperature, pressure, etc.). Structure and electronic properties of ZnSe/GaAs interfaces are probed using HREELS and nonlinear optical spectroscopies. The specific couple studied in this project is used in diodes, LEDs, lasers, and other optoelectronic devices. Improved processing techniques should lead to expanded uses. Additionally, much of this effort may be generalizable to other II-VI / III-V heterojunctions.
